diff --git a/flake.nix b/flake.nix
index 3b565c4..844c330 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,7 +5,7 @@
     # Nixpkgs
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
     sops-nix.url = "github:Mic92/sops-nix";
-    simple-nixos-mailserver.url = "gitlab:simple-nixos-mailserver/nixos-mailserver/master";
+    simple-nixos-mailserver.url = "gitlab:simple-nixos-mailserver/nixos-mailserver/nixos-23.11";
     flake-utils.url = "github:numtide/flake-utils";
     plasma-manager.url = "github:pjones/plasma-manager";
     plasma-manager.inputs.nixpkgs.follows = "nixpkgs";